Skip to main content

Full text of "The Morphology And Evolution Of The Apes And Man"

See other formats

THE SKELETON AND TEETH               I-io
slightly larger than the upper lateral incisors, but the four lower incisors are more nearly equal. All the incisors have small crowns. The canine teeth are lonir
and sabre-like. When the jaws are closed the lower canines pass up into diasteinata between the upper canine and upper lateral incisor teeth. Owing to the locking of the canine teeth there is no great degree £ lateral mobility in the teinporo-maxillary joints.
The upper premolar teeth, have three roots, of which two are external and one is internal. The first tooth has a large external and a small internal en^p; is :s smaller than the second tooth whose cusps are nearly equal in size. The internal cusp is derived from the cingulum, which is a band surrounding the base of the crown. The first lower premolar tooth is larger than
the second, but both have two roots Iving anterior and
j                                          v    t?
posterior in position. The first has a large internal and a small external cusp, but the cusps of the second tcoth are nearly equal.
The upper molar teeth have three roots placed like the roots of the upper premolar teeth. They decrease in size in the order 1, *2, 3; and their crowns are narrow mesially. There are four cusps on each tooth, and an oblique ridge connects the metacone and protocone. The protocone and paracone may be connected. The third upper molar tooth exhibits signs of degeneration. The lower molar teeth have anterior and posterior roots, and the middle of the crowns form basins for the reception of the inner cusps of the upper molar teeth. The second tooth is larger than the first and third. The crowns have five cusps.